Engineers at ISRO are gearing up to test the scramjet engine developed in-house to power the Reusable Launch Vehicle (RLV) due to undergo the first experimental flight shortly.The scramjet engine which uses air breathing propulsion technology for hypersonic flight is scheduled to be test flown in January or February, VSSC Director K. Sivan said here on Friday. Talking to the media on the sidelines of the National Aerospace Manufacturing Seminar (NAMS- 2015) organised by the Society of Aerospace Manufacturing Engineers, he said the scramjet engine would be strapped to a two-stage Rohini sounding rocket for the experimental flight lasting seven seconds. It will be released at a height of 70 km and ignited during the coasting phase.
The basic design of a scramjet has already been evolved.A test launch of the engine aboard a sounding rocket, which will achieve a flight regime of up to Mach 8, will take place some place in June at SHAR, Dr. Sivan said.
"We will soon be testing - may be this June - our air breathing engine fitted to a sounding rocket," Mr Sivan said.
After successfully testing a technology demonstrator of a reusable launch vehicle, Indian Space Research Organisation (ISRO) is planning to test an air-breathing propulsion system, which aims to capitalise on the oxygen in the atmosphere instead of liquefied oxygen while in flight.“The mission to test the technology would be launched either in the last week of June or early July from Satish Dhawan Space Centre at Sriharikota. The mission would be on a sounding rocket,” K. Sivan, Director of the Thiruvananthapuram-based Vikram Sarabhai Space Centre told The Hindu.
The new propulsion system, once mastered, would complement ISRO’s aim to develop a reusable launch vehicle, which would have longer flight duration. The system, involving the scramjet engine, would become crucial while sending up the spacecraft.
According to ISRO, the Dual Mode Ramjet (DMRJ), the ramjet-scramjet combination, “is currently under development, which will operate during the crucial Mach 3 to Mach 9 ascend flight of the launch vehicle.”
I want to ask about this whole idea of collecting LOX on the way up - I'm not sure if ISRO or DRDO are the originators of this idea or if it came from somewhere else, but it sounds weird/absurd to me.To me, it sound like sticking a windmill on the front of your car, and then claiming it will generate power while you drive, and using it to further accelerate your car.One Indian technical paper talks about "liquefaction drag" which requires fuel consumption to offset it. But so if you're getting a bit more drag from collecting LOX and having to spend more fuel to compensate, is there a net benefit from accumulating oxygen for later use in getting the rest of the way to orbit?From what I remember way back on that AVATAR SSTO study, they felt the LOX collection on the way up was some kind of key enabler to make SSTO feasible. They felt there was some narrow operating window within which this could all work.Anybody know anything on this?
But who said anything about "accumulating LOX"? Scramjet uses atmospheric oxygen as oxidizer to operate. There's no liquid O2 up above.
Quote from: ss1_3 on 05/27/2016 10:05 amBut who said anything about "accumulating LOX"? Scramjet uses atmospheric oxygen as oxidizer to operate. There's no liquid O2 up above.I'm not talking about your regular scramjet that only immediately burns the oxygen as it sucks it in. I'm talking about this idea (that's been discussed in Indian circles at least) that you can additionally also even collect some of the oxygen and store it for later, for when you rocket the rest of the way to orbit. Is that plausible, or is it too weird?
In all the slides above and the referenced news articles, I don't see LOX being talked about. Can you cite any paper or news links where they are talking about "collection"? How'd that even qualify as scramjet or ramjet?
The idea is to develop a spaceplane vehicle that can take off from conventional airfields. Its liquid air cycle engine would collect air in the atmosphere on the way up, liquefy it, separate oxygen and store it on board for subsequent flight beyond the atmosphere. ...During this cruising phase, an on-board system would collect air from the atmosphere, from which liquid oxygen would be separated and stored and used to burn the stored hydrogen in the final flight phase to attain orbit.
You really need to read up on Skylon and the SABRE... http://www.reactionengines.co.uk/
Quote from: Rocket Science on 05/27/2016 04:06 pmYou really need to read up on Skylon and the SABRE... http://www.reactionengines.co.uk/Yeah, sure I've read about Skylon, SABRE and its pre-cooler technology - watched the documentary and all that - but I never realized it was collecting oxygen for later use. I thought it was just burning the air immediately, and that it had a separate onboard LOX supply that was pre-loaded. I thought the pre-cooler was just to keep parts from melting. Ah, so now I know better.
Unlike conventional rockets, Air Breathing Propulsion System makes use of atmospheric oxygen for combustion thus resulting in substantial improvement in payload fraction and reduction in overall cost. Though the developmental activities towards dual mode ramjet engines and their associated technologies have been initiated, the present focus is on development of scramjet engine and flight testing the same in a cost effective method using Advanced Technology Vehicle (ATV).The major highlights of development in this regard in the year include realisation of Avionics module and Energiser for Pilot Flame Ignition Unit, Qualification of Silicon Carbide coated Carbon/Carbon leading edges through hot tests at 6 MW Plasma Wind Tunnel Facility and commencement of Integration activities on scramjet engine frame and engine flow duct.Rapid expulsion tests using gaseous hydrogen modules for the Titanium lined Carbon wrapped Gaseous Hydrogen bottles to be housed in Fuel Storage and Feed System was successfully conducted at IPRC, Mahendragiri. Acoustic characterisation test of Engine and Fuel Feed System as mounted to sustainer vehicle configuration was carried outat NAL, Bengaluru.Assembly and Integration of Air Breathing propulsion modules, namely. Scramjet Engines and Fuel Feed System for ATV-D02 flight, are in progress. The demonstration flight of advanced Technology Vehicle carrying active scramjet engine flight is targeted in 2016.
Advanced Technology Vehicle and Sounding Rocket Project (ATVP)Advanced Technology Vehicle (ATV) has the unique capability to carry a payload of 200-400 kg up to an altitude of 800 km. Ascent of ATV in a direct vertical profile is an excellent platform for studies related to upper atmosphere and short duration transient phenomena in the atmosphere. ATV provides a cost effective platform for the study of micro-gravity providing a dwell time of 10 minutes at levels better than 100 micro-g, which can be used for microgravity experiments in fluid physics, combustion research, material sciences, biology and also to perform precursor experiments for launch vehicles, satellites and human spaceflight mission.Advanced Technology Vehicle (ATV-D02) flight: ATV-D02 is the sounding rocket identified for carrying the twin scramjet air breathing engines for demonstrating supersonic combustion experiment scheduled during first quarter of 2016. The major activities completed towards this mission is Acoustic Test of ATV-D02 sustainer vehicle configuration at National Aerospace Laboratories (NAL), Bengaluru, booster motor casting and spin test of Advanced Telemetry System with Sequencer. The Sustainer motor is ready for casting and the Aero dynamic and structural load studies have been completed.
Was the last sentence sarcasm?
Yes, melting of parts is an big issue, but so is the physics of the combustion. You have to get the right flow rate into the combustion chamber, so how far up the temperature/pressure curve would the mass flow rate out from the turbocompressor have to operate at if the inlet temperature was already at stagnation temperature? I don't think it was suggested anywhere Skylon was collecting O2 for later use. My understanding of Rocket Science's first reference to Skylon was that if ISRO wants to collect significant amount of O2 for use, it will face the same technical challenge as Skylon, that being the cooling of the air stream before you can do anything useful with it. Skylon does not store the air, it burns it as it passes through. If ISRO wants to store up LOX, you have to first make an equivalent pre-cooler to Skylon, then you probably have to add another compression & expansion step to reject even more heat from the working fluid before you collect your first drop of LOX. So from a technical standpoint, sure you can make LOX from air, but you are talking about making tons of it in a matter of 60-90 seconds of your flight regime that you are low enough in the atmosphere to even have access to enough air to make a difference. So what would the trades be for all the additional equipment ( compressor, expansion chamber+heat exchangers, etc. vs. just building a sufficiently sized LOX tank that you load during ground ops?
There are also so-called liquid air cycle engines (LACE) that would liquify air and store that for use by rocket engines to use once the air was too thin for the scramjet to work well:https://en.m.wikipedia.org/wiki/Liquid_air_cycle_engineThe link to the comments by Henry Spencer discussing just how difficult it would be to actually get this to work is worth following:http://www.islandone.org/Propulsion/SCRAM-Spencer1.html
So from a technical standpoint, sure you can make LOX from air, but you are talking about making tons of it in a matter of 60-90 seconds of your flight regime that you are low enough in the atmosphere to even have access to enough air to make a difference. So what would the trades be for all the additional equipment ( compressor, expansion chamber+heat exchangers, etc. vs. just building a sufficiently sized LOX tank that you load during ground ops?